The present invention relates to debris traps used in combination with automatic swimming pool cleaners. Automatic pool cleaners typically operate by connecting the cleaner to the water inlet of the swimming pool filter system skimmer. The skimmer is connected to the swimming pool filter and the filter pump. Water is drawn into the skimmer by the filter pump and then passes through a sand filter or filters. The water is then discharged back into the swimming pool.
Automatic pool cleaners typically are connected to the skimmer by a long flexible hose. This hose generally is made up of several sections connected by friction couplings. Water is drawn through the pool cleaner, the flexible hose and into the skimmer inlet by the filter pump. This water movement not only draws dirt and debris into the pool cleaner (and ultimately through the pool filter), but also serves as a motive force to move the pool cleaner about the horizontal and vertical surfaces of the pool randomly and to help hold the pool cleaner against the sides of the pool being cleaned.
Pool cleaners typically ingest a large amount of debris that has fallen into the swimming pool, some of which can be relatively large, such as leaves, twigs, pine straw and insects. If the debris is allowed to be drawn into the pool filter system, the debris can prematurely congest the pool filter or interfere with the operation of the pool cleaner regulator valve. Therefore, it is desirable to provide a device for trapping this debris before it enters the skimmer.
The use of leaf or debris traps in combination with pool cleaners is well-known. Such traps typically have a housing made in two halves, with an inlet in one half and an outlet in the other half, to allow the interior of the trap to be cleaned of accumulated debris. A filter is suspended coaxially within the housing between the inlet and the outlet. The debris trap is spliced into the pool cleaner flexible hose near the filter system skimmer so that the debris trap floats just under the surface of the water. A rubber seal is used between the halves to prevent air from entering the otherwise closed system.
This typical arrangement has several disadvantages, however. First, the debris trap generally must be disconnected from the flexible hose for cleaning. Removing the debris trap requires turning off the filter pump and increases the likelihood that air will enter the otherwise closed filter system, thereby causing the filter pump to lose its prime. In addition, a portion of the seal is always exposed to the air, which also increases the likelihood that air will enter the system because of seal failure or contamination. Further, because the filter basket is interposed directly between the inlet and the outlet and directly within the flow stream, debris tends to be forced deep into the filter grid, making it difficult to remove the debris from the filter, and plugging the filter, which reduces the flow through the filter and can render the pool cleaner inoperable. Dirt and other debris also tend to accumulate at the seal, increasing the likelihood that the debris will force the seal away from one or both halves during as the pump operates.
Other filters used in connection with industrial applications rather than swimming pool cleaners include, for example, the "T"-type strainer shown on Form No. RV 900 of RonVik, Inc. Such strainers do not permit removal of the entire filter housing, however, making cleaning of the interior of the housing difficult. These strainers also lack any relief valve or drain permitting water to enter the trap when the mechanism becomes clogged, essentially precluding their successful use with swimming pool cleaners.